It is never 100% certain in making an ID from a photo of a bird. The following is what I think I know.
Photo # 22 is a male Common Nighthawk. The wings are pointed and P-10 is as long or longer than P-9. The wingbars are bold white, large and about 40% of the distance of the wing from the tip. The throat is bold and white.
Photo # 26 is a male Lesser Nighthawk (90% sure). The wings are rounded and P-10 is shorter than P-9. The wingbars are white and only about 34% of the distance of the wing from the tip. The throat is buffy and does not stand out.
Photo # 21 is a male Lesser Nighthawk (90% sure). The wings are rounded and P-10 is shorter than P-9. The wingbars are white and only about 34% of the distance of the wing from the tip. Throat is off white.
Photo # 27 is also a male Lesser Nighthawk (75% sure). Lighting is now poor so field marks are not as easy to see. Wings are rounded and again P-10 is shorter and P-9. Wingbars appears to be in the position one would expect for a Lesser Nighthawk.
By mid to late June a good percentage of nighthawks seen in the early evening as adult males. Females are incubating eggs as males play a minor or no roll at all in incubation.
These photos were taken the last week in June.
Female Lesser Nighthawks are, by far, the easiest ID, Lesser verses Common. We have seen females around this year but were not in the right place at the right time to get photos.
Female Common Nighthawks and male Lessers are quite difficult. As Ron suggested it is really useful to see the nighthawks in flight. There are many good photos of both nighthawk species you can access via the internet.
Within a week or so juveniles will be flying. At this time I have little hope of convincing myself as to what species it may be. Juvenile CONIs look to much like LENIs and even their clumsy flight can be similar to LENIs.